As a communication system in which mobile terminals and base stations perform wireless communications, a communication system using relay stations has been suggested. In such a system, base stations communicate with mobile terminals via relay stations. Accordingly, communications can be performed with mobile terminals the radio waves from the base stations cannot reach. That is, the communication areas of the base stations can be made wider. Also, as base stations and relay stations cooperate to communicate with mobile terminals, the communication rate with mobile terminals can be made higher (Non-Patent Document 1, for example).
Non-Patent Document 1: J. N. Laneman, “Cooperative Diversity in Wireless Networks: Algorithms and Architectures,” Ph. D. Thesis, Massachusetts Institute of Technology, Cambridge, Mass., Aug. 2002